There's a shrill blast from a steam train's whistle, a puff of smoke, a name – Hugh Bonneville – across the screen. I think I know what kind of beast we're dealing with here. Ah, here's the magnificent gothic country pile, great fir trees, lawns, a gravel drive, kedgeree and ironed newspapers for breakfast, more big names – Maggie Smith, Elizabeth McGovern. It is conceived and written by Julian "Gosford Park" Fellowes. Downton Abbey (ITV1, Sunday) is essentially Gosford Park, in instalments, for television.

It's set a little earlier – we start off in April 1912. The Titanic has just gone down, taking with her two male heirs to Lord Grantham's title and estate. Heir loss – it is a problem back then. Girls don't count for anything – can't even vote, let alone inherit property. A few other things haven't happened yet, some bad (world war), others wicked (jazz). It is, in a word, Edwardian, even though Edward VII himself went down a couple of years before.

Like Gosford Park, Downton Abbey is another study by Fellowes of the English class system. And again it's as complicated below stairs as it is above. The difference between a valet and a footman is as important as the difference between a duchess and a countess. Carson (Jim Carter) the toady butler, and Mrs Hughes (Phyllis Logan) the severe housekeeper, are at least as much in charge of the place as Lord and Lady Grantham (Bonneville and McGovern). Certainly they are more aware of what's going on; maybe they are better prepared for the change that's surely coming.

I can't get too excited about some of the class stuff. It's clearly important to them whether it's acceptable for a duke to be served by a maid (apparently not), but frankly I don't give a damn. Likewise about the entail – the complex legal settlement that determines who's entitled to whose money and which title when so-and-so dies. But it's central to what's going on. Still, it is possible to ignore a lot of that, because there's plenty of other stuff happening – warring sisters, scheming footmen, plotting, bitching, back-stabbing and bounty hunting. There's even a gay duke and an upstairs-downstairs relationship (does social position determine sexual position, I wonder?). And hanging over it all is the feeling that things aren't going to be as they are for much longer. Momentous stuff is going to happen, both in Downton Abbey and the world outside.

It's beautifully made – handsome, artfully crafted and acted. Smith, who plays the formidable and disdainful Dowager Countess (whatever one of those is), has a lovely way of delivering words, always spaced to perfection. This is going to be a treat if you like a lavish period drama of a Sunday evening. Is it really on ITV1? It feels just a little bit too, well, classy.

There's some amazing stuff going on in All New Celebrity Total Wipeout (BBC1, Saturday). First of all someone called JK from something called JK and Joel is the first celebrity ever to get over the big red balls. Not get over as in recover from emotionally, but actually physically get across them, without bouncing off and falling into the water. And then, just minutes later, someone called Sarah Cawood from I don't know what goes and does it as well. Two in one show, incredible. And that still leaves eight to go in to the water in a very undignified manner. I don't think I'll ever tire of watching people attempt the balls. The whole of Total Wipeout in fact. It's my total guilty pleasure; I love it. Who cares that I've never heard of any of the celebrities taking part?

And a special thrill this week: my own profession gets a little mention. Richard Hammond is talking about the Cradles of Doom, a sort of giant swing that has to be crossed (all the obstacles are the same – they move, making it highly likely that the contestant will fall off it and into the water). "Like an angry TV critic, this monster is determined to send celebrities plummeting to their doom," he says. "One little mistake crossing the pendulums is all it takes to send the celebrities screaming into the murky depths of Z-list land." He means the water. And I'm not sure where he thinks they're starting from. But still, being compared to a celebrity Cradle of Doom, by Richard Hammond, on Total Wipeout! Do honours come any greater?

• This article was amended on 27 September 2010. The original said that Julian Fellowes directed Downton Abbey. This has been corrected.

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